Combined Ozonation Pretreatment And Anaerobic Digestion For Beer Industry Sludge

With the widely application of aerobic biological technology, excess sludge generated increasingly. Excess sludge mainly composes by water, microorganism and other inorganic compounds. Because excess sludge contains a great deal of organic matter, it needs to stabilize before the ultimate disposal. Anaerobic digestion is the most widespread sludge treatment techniques, it can achieve the stabilization, reduction and reutilization of excess sludge at the same time. But all the existing sludge anaerobic digestion techniques have the deficiencies like slow reaction rate, low yield of biogas and reaction instability.In this study, excess sludge is treated by applying the combined technique of ozonation pre-treatment and two-phase anaerobic digestion. The experiment first compares TSS, VSS, SCOD, VFAs, pH of sludge mixture which is treated by different ozone concentrations and ozone doses, finds out the best ozone concentration and ozone dose in the ozonation pre-treatment. And then uses excess sludge in the beer industry as feed, cultivates and domesticates anaerobic microorganism in the three same reactors. After that names those three reactors as the single phase reactor, acidogenic-phase reactor and methanogenic-phase reactor respectively, and switches ozonation pretreatment sludge as the feed of single phase reactor and acidogenic-phase reactor, and the disposal material of acidogenic-phase reactor as the feed of methanogenic-phase reactor. Acidogenic-phase reactor and methanogenic-phase reactor constitute two-phase system. In order to ensure the same VLR of the single-phase system and two-phase system during the experiment, the feed of acidogenic-phase reactor is two times as single phase reactor.The results indicate that the optimum pretreatment condition is the ozone dose,0.10g O3/g SS; the gas flux,100L/h. At this condition, SCOD achieves the maximum,5.70×103 mg/L; the removal efficiencies of TSS and VSS of the sludge are58.6%and62.4%respectively, and those two values are near to the corresponding maximum efficiencies of TSS and VSS; pH is5.00, and it can adjust to the right pH range by adding NaHCO3.Compared with the single-phase system, the two-phase system has higher and more stable alkalinity, better adaptability of feed and impact resistance and higher gas yield, the total gas yield of the two-phase system is3.48times as the single-phase reactor. Moreover, the removal efficiencies of TSS and VSS in the two-phase system are higher about40%and30%respectively than those of TSS and VSS in the anaerobic digestion system which is not treated by ozone oxidation.The combined technique of the ozonation pre-treatment and two-phase anaerobic digestion is matched effectively than the combination between the ozonation pre-treatment and the single-phase system, and it can provide a new way with the sludge treatment in the beer industry.